(a) Technical Field
The present invention relates to a liquid crystal display device, and more particularly, to a vertical alignment liquid crystal display.
(b) Description of the Related Art
Liquid crystal displays (LCDs) are now widely used as one of the prominent flat panel displays. A liquid crystal display device has two display panels on which field generating electrodes, such as pixel electrodes and common electrodes, are formed, and a liquid crystal layer is interposed between the panels. In a liquid crystal display device, voltages are applied to the electrodes and an electric field generated across the liquid crystal layer determines the alignment of liquid crystal molecules. By controlling the incident light polarization according to the display data signals a video image is displayed on the LCD panel.
Among the liquid crystal displays, a vertical alignment (VA) mode liquid crystal display has an advantage of a high contrast ratio and a wide reference viewing angle, which is defined as the viewing angle at a contrast ratio of 1:10, also known as the intergray luminance inversion limitation angle. In VA mode liquid crystal display, the axes of the liquid crystal molecules orient perpendicular to the upper and lower display panels when an electric field is not applied thereto.
In the vertical alignment (VA) mode liquid crystal display, cutouts or protrusions may be formed on the field-generating electrodes to widen the viewing angle. The cutouts or protrusions modify the orientation of the liquid crystal molecules nearby, thus widening the reference viewing angle.
However, the lateral visibility of the vertical alignment (VA) mode liquid crystal display is lower than the front visibility. For example, with a patterned vertically aligned (PVA) liquid crystal display with cutouts, the image becomes brighter toward the lateral side, and in a worst case, the luminance difference between the high grays is eradicated so that the picture image may appear to have collapsed.
Information disclosed in the Background section is meant for understanding the invention background and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.